1. Field of the Invention
This invention relates generally to a seat, and, more particularly, to a seat with a pair of moving seat platforms and platform improvements enabling a portable one and two platform seat which can be easily transported, and particularly to a seat which can be used on and interfitting upon a variety of surfaces.
2. Description of the Related Art
Most seats in the past did not promote seated occupant movement analogous as to that which happens when a standing person shifts his weight from side to side. This adjustment enables a standing person to shift weight from one side of the pelvis to the other. Conventional seating doesn""t enable a person to shift weight in this fashion while seated. Conventional seating thus does not permit much weight shifting from side to side and thus forces the weight of the user to be borne too much and too long by the flesh of the buttocks and thighs, and not enough by the ischial tuberosities (xe2x80x9cseat bonesxe2x80x9d). Further, seats that do not promote occupant movement will by converse action cause the seated occupant to sit in a constrained or static posture. This can lead to a number of health-related problems. For example, constrained occupant seating postures can cause joint impairments (arthritis), inflamed tendon sheaths (tendinitis, peritendinitis), chronic joint degeneration (arthroses), and muscle pain (e.g., when the occupant shifts weight on the seat bones, from side to side, or leans to one side, the occupant stresses his or her back muscles to remain adequately supported on the seat).
Prolonged static seating has also been linked to back problems because of the prolonged static pressure on the spine. Prolonged static pressure on the spine impairs fluid flow from the discs, impairing glucose transport, disc nutrition, and the elimination of waste products.
Constrained occupant postures also cause poor circulation. Edema of the lower legs is commonly induced by lack of movement. Leg edema is problematic because local pooling of the blood increases venous pressures to the heart, blood pressure, and heart rate. Edema may predispose the occupant to varicose veins, hemorrhoids, and other peripheral venous disorders such as cold feet. Another circulation problem resulting from seats that do not promote occupant movement is deep venous thrombosis caused by the formation of venous clots in the legs. These blood clot formations occur from sitting in a static position for long periods of time. Other circulation problems occur when certain parts of the occupant""s posterior or legs experience greater pressure than the portion of the seat, especially the front, digs into the other seated portions of the occupant. This occurs when a portion of a seat, especially the front of the seat, impinges the posterior or back of the legs of the occupant, or if the occupant leans more towards one side of the seat than the other side. Either effect can result in decreased circulation to the lower body. These concentrated forces and effects on the legs and posterior inhibit circulation and lead to discomfort.
Some seats have been designed to promote occupant movement and improve the comfort of the seated occupant. Some of these seats include a pair of seat platforms that move independently of each other. Each seat platform rocks in a see-saw manner on a fulcrum. In one of these seats, the fulcrum also allows vertical movement of the seat platform as the seat platform slides backwards and forwards. The independent seat platforms are designed to be self aligning, and allow the posterior of the occupant to move normally and independently without restraint, improving seat comfort.
The problem with these seats is that they are not comfortable for multiple seating applications and environments (e.g., office, home, automobile, etc.). In most seating environments, these seats do not properly distribute the weight of the body being borne by the ischial tuberosities and the residual weight of the posterior and thigh over the two seating platforms during different seat positions (e.g., one leg up, both legs up, both legs down, legs crossed, etc.). This causes discomfort and circulation problems. Also, in most seating environments, the seats did not allow the exercise necessary for the muscles, tendons, and ligaments of the lower back, pelvis, and thigh areas. This leads to circulation problems, flexibility problems, and back problems. Further, there was no adjustability for varying weights and sizes of seat occupants, nor no small fine tuning possible for necessary comfort by the individual seat user.
In terms of the infra structural existence of conventional seating, seating which is utilizably available, as well as purchasable is overwhelmingly of a type which is deleterious to the proper support of the human structure. One of the main obstacles to proper seating is the lack of complementary seating which can be used with the existing seating infrastructure. What is needed is a mechanism, process or structure which enables existing seating to be retrofitted with proper seating or which enables proper seating to be added to the conventional seating infrastructure.
An object of the present invention is to overcome the above-described difficulties of static seating and particularly in overcoming a current static seating condition, including traditional flat, over padded and contoured seating which by cradling constrains the posterior, such disadvantages of which are found in the overwhelmingly large numbers of conventional seating.
An aspect of the present invention involves the recognition that a seat with a single one, or a pair or more of seat platforms or assemblies that optimal seating comfort is achieved by providing the seat assemblies at a predetermined neutral angle appropriate for the particular application of the seat. Such neutral angle is defined as the angle, relative to horizontal, at which the seat assemblies are initially oriented before any external forces are applied to the seat. It is further recognized that each seat assembly should rock and move vertically up to a predetermined amount corresponding to a neutral angle discussed more fully below.
Another aspect of the present invention involves four additional recognitions. First, in greater positive neutral angle seating applications (leaned-back seating), the amount of rocking and vertical movement should be greater. Second, in smaller positive neutral angle seating applications, the amount of rocking and vertical movement should be smaller. Third, in greater negative neutral angle seating applications (leaned-forward seating), the amount of rocking movement should be greater, but the amount of vertical movement should be smaller. Finally, in smaller negative neutral angle seating applications, the amount of rocking and vertical movement should be smaller.
An additional aspect of the present invention involves a seat with either a pair, multiple, or a single moving seat assembly. A motion mechanism allows vertical motion and rocking motion in each seat assembly. The seat assembly is provided at a neutral angle based on the application of the seat. The total amount of rocking motion and vertical motion allowed depends on the neutral angle of the seat assembly. This combination causes the weight of a seated occupant borne by the ischial tuberosities and the residual weight of the posterior and thighs to be distributed optimally over the two seating assemblies, regardless of the occupant""s seated position. The combination also allows the muscles, tendons, and ligaments of the lower back, pelvic, and thigh areas to be exercised, improving fluid flow (e.g., blood circulation), alertness, flexibility, and inhibiting back pain.
In particular, the inventive seating of the claimed invention is able to provide the above advantages in an extremely low profile, safe, portable, traditional office seating, transportation (automobile, aircraft, trucking), or almost any seating structure. Single application, dual or multiple independent movement and even forward movement which is somewhat independent of rear movement is achievable in a light-weight, portable and built-in fashion, and with features which are not easily implementable in a low height structure. The inventive seat in one embodiment has a system which includes a somewhat exponential, somewhat stepwise, increasing spring resistance, which is important both as a requisite for narrow height seating and an important achievement despite the narrow height space. The vertical displacement of the seat of the invention is achieved through springs, polymeric members and rubber stops, along with some adjustabilty achievable by a circular stepped structure for engagement of the polymeric members. As such, the engagement point of the polymeric members adjusts the point at which the spring resistance begins going exponential.
The single, two or multiple platform version of the seat of the invention includes a lateral direction stabilizing mechanism which guides each platform on each side to facilitate optimum down/up movement, and independent rocking from back to front. It also prevents encroachment of either platform in the direction of the other platform. This prevents scissoring of the seat members and yet provides the proper amount of platform freedom. The lateral direction stabilization mechanism also facilitates, along with seating halves or other section, which at minimum bow or pivot at the middle, system in which the seating acts differently at their forward ends than at their rearward ends. A firmer more even forward support, along with more accommodating rear support, is unusually inventive in a seat having limited height.